Abstract

Rays no longer just represent the trajectories traversed by a beam of light but they describe the general transport properties of high-frequency fields. Viewed within the framework of wave spectra, ray fields are localized spectral objects synthesized by constructive spectral interference. The spectral flesh within these objects can be trimmed to the bare bones for the simplest type of ray field, a local plane wave, but must be augmented in ray transition regions near caustics, shadow boundaries, diffraction centers, etc., where more-intricate wave phenomena occur. Thus ray tracing along ray paths generally involves a succession of bare-bones and fleshed-out (uniformized) spectral entities that can furnish in a highly effective manner the amplitude and the phase of the high-frequency field in a complex environment. Relevant spectral concepts are discussed, including those for complex rays that describe evanescent fields and Gaussian beams and those leading to collective treatment of multiple reflected or diffracted contributions.

© 1985 Optical Society of America

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